refactor: move all port management code to standalone ports plugin

This change makes interacting with port mappings more clear - folks might previously set the port mapping to the proxy type or vice-versa.

The existing proxy:ports* commands still exist but will show a deprecation warning for a single minor release.

plugins/ports/.gitignore

@@ -0,0 +1,7 @@
+/commands
+/subcommands/*
+/triggers/*
+/triggers
+/install
+/post-*
+/report